DESCRIPTION (provided by investigator): Human papillomavirus (HPV) infection is the central cause of cervical cancer. Most sexually-active women acquire HPV infection over a lifetime. The vast majority of these infections are transient, but a small proportion becomes persistent and eventually lead to pre-cancerous lesions. There is great enthusiasm concerning the application of HPV testing in cervical cancer screening and use of HPV vaccination. Yet, these strategies are hampered by the paucity of information on the sexual transmissibility of HPV. The HPV Infection and Transmission among Couples through Heterosexual activity (HITCH) cohort study was funded by CIHR in 2004 to further our understanding of the transmissibility of HPV. Specific aims are: (1) to describe the prevalence and type-specific concordance of HPV infection between young women and men in heterosexual couples; (2) to finely characterize and quantify risk factors for incident HPV infection among young women and men; (3) to estimate rates of male-to-female and female-to-male HPV transmission; (4) to identify behavioural risk factors and biological determinants for HPV transmission upon exposure; and (5) to characterize HPV infection in the oral tract and fingers and its agreement with genital infection and partner's infection status. HITCH's population consists of young (aged 18-24) women attending McGill and Concordia universities and neighboring junior colleges in Montreal and their male partners. 600 couples will be recruited for assessment of sexual histories and HPV DNA testing at baseline and at multiple opportunities during follow-up. The study will also enroll new partners acquired by the women during follow-up. Internet- based, self-administered questionnaires will be used to collect sexual behavioral information. HPV DNA typing will be done by the PGMY09/11 polymerase chain reaction protocol and typing of selected HLA loci will be done by allele-specific PCR assays. Type-specific concordance and discordance will be analyzed using Monte-Carlo simulation and maximum likelihood methods. Rates of HPV acquisition and transmission over time will be analyzed using Poisson and Cox regression, and with generalized estimating equation techniques. There are two unique features of the study. It is the first large-scale study of HPV acquisition that involves sexual partners. Worldwide, HITCH is presently the largest cohort study of couples. Second, it is the only study to limit recruitment to new couples, a time at which most transmission is believed to occur. Moreover, HITCH will provide a much finer level of detailed sexual behavioral information than previous studies. Our findings are likely to impact on HPV and cervical cancer prevention efforts, including behavioral strategies to reduce risk and improved estimates of transmission parameters to be used in models of the cost effectiveness of HPV-based screening and immunization. PUBLIC HEALTH RELEVANCE: Genital HPV infection is the most common sexually transmitted infection today. Most such infections are not noticed or cause only external warts. Warts are difficult to treat and lead to social stigmatization. Some HPV infections may lead to cervical cancer. The proposed study will help our understanding of the transmissibility of HPV infection, which will permit cost-effective strategies based on HPV screening and HPV vaccination to prevent cervical cancer and other HPV-associated diseases.